Chuck.



' W. LE- R. BRYANT.

CHUCK.

, APPLICATION FILED OUT. 22, 1910. 1,675,756. Patented Oct. 14, 1913.

2 SHEETS-SHEET 1. .j 38 693527 40 2s 4/ nu Z1 5 W. LE R. BRYANT.

OHUGK.

APPLICATION FILED OUT. 22, 1910.

Patented Oct. 14, 1913.

2 SHEETS-SHEET 2.

COLUMBIA PLANOGRAPH co, WASHINGTON. n. c.

WILLIAM LE BOY BRYANT, OF SPRINGFIELD, VERMONT;

CHUCK.

Specification of Letters Patent.

Patented Get. 14, 11913.

Application filed Gctober 22, 1910. Serial No. 588,427.

To all whom it may concern Be it known that I, WVILLnm r Ln ROY BRY-ANT, a citizen of the United States, of Springfield, in the county ofWindsor and State of Vermont, have invented certain new and usefulImprovements in Chucks, of which the following is a specification.

This invention has relation to chucks for holding metal during theoperation of turning or grinding.

In modern practice, a bar or other piece of metal is turned toapproximately the diameter or diameters desired, and in many cases isthen subjected to a hardening process. Such pieces of metal thus turned,or turned and hardened, are then ground accurately to the desireddiameter. Both in turning and in grinding it is practically impossibleto rechuck the work; that is to say, after placing it in the chuck andsubjecting it to one operation, it is exceedingly difficult to replaceit in the chuck for a second operation without an error due to theinaccuracies in the periphery of the Work, especially where the work hasbeen hardened. Where the work is to be finished, as by fine turning orby grinding, it is highly desir able, if not essential, that the workshould be centered as accurately as possible with reference to the axisof the chuck and without loss of time. I-Ieretofore it has beenpractically the universal custom to provide the chuck with a pluralityof jaws to take bearing on the periphery of the work, and to move thesejaws simultaneously toward the center. lVhere this is done, however, itis quite apparent that some of the jaws will engage the work whileothers will not, except in the case of the three-j awed chucks. In theformer case, the aws are adjustable independently of each other in orderto secure a bearing of all of the jaws upon the work. In both cases,however, it has been impossible as a practical matter to center the workwithout the expenditure of a great deal of time on the part of theoperator, and, as a result, an excessive amount of metal is necessarilyremoved in order that the finished work may be concentric with the axisupon which it is rotated.

The object of the present invention is to provide a chuck in which Iobviate, to a great extent, error in centering the work due toinequalities in the periphery of the work itself, and enable theoperator to operate the jaws simultaneously. This I accomplish byarranging the jaws in pairs and employing for. each pair an equalizermovable about a point or fulcrum at which power is applied to theequalizer, so that the two jaws of the pair will have a differentialmovement whereby both will be caused to bear equally upon the peripheryof the work. Forinstance, where six jaws are employed, arranged in threepairs, the jaws of each pair being operated by an equalizer, I secure ageneral average of en gagement of the jaws with the work which morequickly and accurately approximates a circle about the center of thework than has heretofore been possible. The equalizers are operatedsimultaneously to move the jaws into engagement with the work, theequalizers, as stated, being capable of a rocking motion approximatelyabout the point where the force is applied to operate them. I provide inthis way what I term a three-point bearing; that is to say, a point onwhich the equalizer bears and about which it is adapted to rock, andseparate points at which the jaws bear either directly or through themedium of some power-transmitting device, so that all the jaws bear withsubstantially equal pressure upon the periphery of the work.

I have illustrated the invention as being embodied in a six-j aw chuckwith an equalizer for each pair of jaws and means actuated by acontroller for simultaneously operating the equalizers, but it will beun derstood that th invention is not limited to any particular number ofjaws and that it may well be embodied in a chuck having a greater orsmaller number of jaws, it being understood of course that the jawsshould always be arranged in pairs so that there will be an even numberof them. In illustratino' the invention, I have also shown a certainfeature of improvement, to wit, the specific means for transmittingpower from the equalizers to the jaws to effect movement of the latter,and certain other features, all of which are described in theaccompanying specification and pointed out in the appended claims.

Referring to the drawings, Figure 1 represents in longitudinal section asix-jaw chuck embodying the invention. Fig. 2 represents a frontelevation of the same. Fig. 3 represents a rear elevation of the chuckwith the spindle and controller removed. Fig. t represents a top view ofa portion of the chuck and illustrates one of the jaws and the rocker.Fig. 5 illustrates a section through the chuck body. Figs. 6 and 7illustrate one of the rockers. Figs. 8, 9 and 10 represent respectivelya rear elevation, a front elevation and a side view of the equal izers.Fig. 11 is in the nature of a diagrammatic View to illustrate theoperation of the equalizer, and shows the controller, an equalizer, andtwo. of the pins which transmit power from the equalizer to the jawsoperated by the equalizer.

On the drawings, 20 indicates a spindle which may be of any desired typeor design such as utilized in lathesor grinding machines, and to whichthe chuck body is attached in any desirable way. It is mounted insuitable bearings, of which one is illustrated at 21. The details ofmounting the spindle are unessential and form no part of the presentinvention. In the end of the spindle there is: a slightly tapered recess22 which is inserted a bushing 23 socketed to receive a slidablecontroller 24L which consists of a cylindrical pin having afrustoconical or tapered projecting outer end, its axis being coincidentwith the axis of rotation of the spindle and chuck. Against the innerend of the controller bears a screw bar 25 equipped with a hand wheel 26by which it maybe rotated to move the controller longitudinally of thespindle. Of course it will be understood that in lieu of the specificform of controller and of the screw bar for operating it, I may utilizeany other mechanism that is convenient or desirable.

The chuck body is indicated at 27 and in its face it has radialguideways for the reception of a plurality of slides indicated at 28.The guideways have tongues taking in the grooves in the sides of theslides as ordinarily. A shouldered 29 is secured to the front of eachslide by any suitable fastening devices, such, for instance, asshouldered screws 30 and dowels 31 which are utilized to accuratelylocate the jaws upon the slides. As illustrated, each slide is providedwith three threaded apertures for the reception of the screws and withtwo apertures for the reception of the dowel, so that the jaw is capableof adjustment to two different positions on the slide. In the rear ofeach guideway there is a radial socket 32 for the reception of adjustingscrews Each screw, as shown, is exteriorly threaded and engagescomplemental threads on the inner face of its adjacent slide, and it isformed -at its end with a polygonal aperture 34:

into which a too-l may be inserted, whereby it may be rotated to effectan independent adjustment of the slide and aw with which it isassociated. It will be observed that each adjusting screw is hollow forthe r ception of a strong helical spring 35, one end of which bearsagainst the chuck body,

said lugs are levers or rockers 39. .rockers are illustrated in detailin Fig. 6,

and the other end of which bears against the end of the socket in thescrew so that its tendency is to force the screw outwardly. As a matterof detail, there is inserted in the socket in each screw a bearing plateor disk 36. The chuck body is provided with a plurality of pairs of lugs37 in its rear, and journaled upon pintles 38 pass-ed through These eachrocker being provided with a convex surface 40 which bears upon the endof one of the adjusting screws 33. By swinging the rockers about theirfulcrums or axes, the i adjusting screws and their associated slides andjaws may be moved radially inward to- ;ward the axis of the chuck.

The rear ends 1 of the rockers are provided with surfaces 4:1

which bear upon the ends of pins 12, as best shown in Fig. 1. These pinsare arranged .radially of said axis of the chuck and are g also inclinedwith respect to said axis. Their outer ends approximate a circle aboutthe axis of the chuck. For sllding each pan of Lpins outwardly tooperate the associated rockers and move the chuck jaws inwardly, Iutllize, what I term, an equalizer. Where a there are six aws andconsequently SlX pins,

I employ three equalizers, and,as illustrated, they take the form ofsegments 43 which are Taking each segment by itself, it is provided witha flat front face a which bears against the flat face of the chuck body,and a tapering convex outer surface 6 against which bear, at twoseparated points, the ends of two of the pins 42.

It is also provided with an inner beveled face 0 which midway betweenits ends rests upon and is adapted to rock about the beveled end of thecontroller 24. By moving the controller longitudinally of its axis, theequalizers may be all bodily moved outward radially of said axis, whileat the same time each equalizer is adapted to rock about its point ofengagement with the controller. The several equalizers are held againstrotation with respect to the chuck body by pins 50 passed through saidchuck body and entering grooves 5-1 in the faces a of said equalizer.

'The springs 35 perform two functions. They thrust the jaws radiallyoutward to inactive position when the controller 24 is withdrawn ormoved to the left, and at the same time they bear with sufficient forceupon the adjusting screws 33 so as to insure at all times the positiveengagement of said screws with the rockers, of the rockerstroller; andtheir force is suflicient, by reason of the taper of the end of thecontroller and the bevel of the equalizers, to move the controller tothe left when the screw bar 25 is rotated to withdraw it.

In Fig. 11, 1 have illustrated diagrammatically one of the rockers, thecontroller and the pins which bear against the rocker. From this figure,it will be apparent that the equalizer is capable of rocking about thepoint with which it is engaged by the controller when it is movedradially outwardly by the controller so that one of the pins may bemoved to a greater distance than the other. The result of thisconstruction is that, when the controller is moved to the right, ortoward active position, the jaws will have a differential movement, someof the jaws being moved to a greater extent than the others, so as tocompensate for inequalities in the periphery in the work and secure apractically uniform bearing of all the jaws upon the work, and thusbring the axis of the work with accuracy into alinement with the axis ofthe chuck. Comparing a chuck of this nature with a three jaw chuck inwhich the jaws are all moved simultaneously into engagement with thework, as are the jaws in the present case, it is plain that in the caseof the threejawed chuck the position of the work with reference to thechuck is determined solely by the engagement of three points with thework and that consequently, if the periphery of the work is not true,the center of the work will not coincide with the center of the chuckunless each jaw be independently adjusted with reference to the others.With a construction such as herein illustrated, however, although thejaws are all moved simultaneously with reference to the work, yet theiriovement is not necessarily to the same extent, those jaws which firstengage the work stopping their movement and the other jaws continuingtheir movement until they likewise engage the work. This divides theerror, as it were, for it multiplies the points of engagement of thejaws with the work and the general average of these points of engagementclosely approximates a true cylinder whose axis is coincident with theaxis of the chuck, and consequently the work is centered with accuracyand without loss of time. Another important result which is secured isthat the work is always engaged by chuck jaws at more than three pointsin its periphery without the necessity of adjusting any one of the jaws;or, in other words, 1 am able to secure the automatic engagement of morethan three jaws with the work without independent adjustment of any ofthem, this being accomplished automatically and merely by the operationof the controller. Each jaw is independently adjustable, however, for amaximum distortion ofthe work, and also for enabling the adjustment ofthe jaws for pieces of work of different diameters. By increasing theextent of movement of the various parts or elements or varying theirrelative proportions, the differential movement of the jaws may be madesuch that they will grasp and bear equally upon the exterior surface ofan article of quite irregular outline.

On the drawing, the jaws are all shown as having been forced inward soas to engage the work, and, in order to release them from the work, itis merely necessary to rotate the screw so as to withdraw it and permitthe movement of the cont-roller to the left to inactive position.

Having thus explained the nature of my said invention, and described away of making and using the same, although without attempting to setforth all of the forms in which it may be made or all of the modes ofits use, what 1 claim is:

1. In a chuck, a rotatable chuck body, a pair of independent radiallymovable jaws, an equalizer for transmitting power at separated points tosaid jaws respectively, and means for transmitting power to saidequalizer at a point between said points.

2. In a chuck, a pair of independent ra dially movable jaws, anequalizer adapted to rock about a fulcrum for transmitting differentialmovement to said jaws at point-s separated from its fulcrum, and meansfor transmitting power to said equalizer substantially at its fulcrumingpoint to move said equalizer bodily, and thereby move said jaws.

8. In a chuck, a chuck body, a plurality of pairs of independentradially movable jaws, and means for moving the jaws into engagementwith the work, comprising a plurality of rocking equalizers movablebodily thereby and arranged about a common center, each equalizer beingarranged to effect the operation of both jaws of a pair, and means foractuating said equalizers.

4:. In a chuck, a chuck body, a plurality of pairs of independentlymovable jaws arranged to move radially of said chuck body, a rockingequalizer for each pair of jaws, and a controller for simultaneouslyactuat-- ing all of said equalizers and thereby effecting thesimultaneous differential actuation of all of said jaws.

5. In a chuck, a chuck body, a plurality of pairs of independentlymovable radial jaws, an equalizer for each pair of jaws, intermediatepowentransmitting devices engaged with each equalizer at separatedpoints for transmitting power to the respective jaws of the associatedpair, and means for simultaneously moving said equalizers, whilepermitting them to rock to equalize the pressure on the jaws.

6. In a chuck, a contr ller, a plurality of equalizers arranged about acommon center and fulcrumed 011 said controller, a pair of radialindependently movable jaws connected with each equalizer at points oneither side of its fulcrum, and means for actuating said controller tomove said equalizers bodily and simultaneously.

7. In a chuck, a tapering controller, a plurality of segmentalequalizers, each having an inner beveled face fulcrumed on thecontroller, a pair of radial jaws associated with each equalizer andoperated thereby at points distant from its fulcruming point, wherebysaid jaws may be moved difierential distances when said equalizer isactuated, and means for moving said controller longitudinally to actuatesaid equalizers.

8. In a chuck, a chuck body having radial guideways, a taperingcontroller, a plurality of radially movable elements with beveled innerfaces engaged with said tapering controller, a plurality of radial jawsarranged to slide rectilinearly in said guideways, pivoted rockers foractuating said jaws, means for adjusting each jaw relatively to itsactuating rocker, and positive power-transmitting means between saidrockers and said elements.

9. In a chuck, a chuck body, radial slides having jaws, rockers pivotedto the chuck body and associated with said slides to opcrate them,slidable pins for actuating said rockers, and means for simultaneouslyoperating said pins.

10. In a chuck, a rotatable chuck body, a plurality of independentradially movable jaws arranged in substantially a circle at the frontface of the chuck body to engage the exterior of the work, a controller,and positive equalizing power -transmitting mechanisms associated withsaid jaws and operated by said controller for simultaneously impartingto said jaws a differential radial movement whereby they may grasp anirregular body with substantially equal positive pressure.

11. In a chuck, a rotatable chuck body, a plurality of pairs ofindependently movable jaws arranged radially on the chuck body, acontroller, and mechanism comprising an equalizer associated with thejaws of each pair and located between said jaws and said controller, andactuated by said controller for imparting a positive simultaneousdifferential movement tosaid jaws.

In testimony whereof I have affixed my signature, inpresence of twowitnesses.

WILLIAM LE ROY BRYANT.

Witnesses:

H. L. ALLEN, P. V. PEZZET'II.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents.

Washington, D. C.

